The present invention relates to a video recording device for recording a digitized video image inputted from a camera into a digital storage memory, and more particularly to a video recording device which is capable of retroactively reproducing a video image (event video image) generated when any event occurs while it records a video image monitored in real time.
An example of the means for recording digitized video information and reproducing the pertinent video image at any timing on demand is a video on-demand system. With video information previously stored in a storage device of a video server system, when a demand for transmitting the video image comes from the reproducing terminal device, the video on-demand system reads the video information according to the demand and sends it to the reproducing terminal device.
An example of the means for recording a video image which is not digitized but inputted in real time is a videotape recorder (VTR). Particularly, a "time lapse VTR" has a purpose of monitoring by video image and intends to review later the video image when any event occurs.
FIG. 8 is a block diagram of a video recording device disclosed in JP-A-2-132599. FIG. 9 is a timing chart of the operation of the device. In this video recording device, a video image inputted from a camera is recorded in a video memory 85 and the recording of the video memory 85 is stopped at a timing responding to an input from a sensor 84, and the video image before and after the sensor 84 produces an event detecting signal that can be displayed. However, since the recording is stopped in response to the signal from the sensor, when the next events occur successively, the video image before and after the event cannot be stored.
Generally, the video on-demand system, before video service is started, previously records and stores video information in the storage device of a video server system. Upon completion of the recording of the video information, the video on-demand system makes video on-demand service. Therefore, the video on-demand system cannot reproduce the video data while they are recorded.
The time lapse VTR, when any event occurs for an object being monitored, can perform its rewind operation to confirm circumstances of the event. In this case, however, the VTR cannot record video data during the rewind operation. Therefore, when another event occurs during the rewind operation, the time lapse VTR cannot have the video data recorded. In addition, generally, the time lapse VTR is not designed for the purpose of reproducing the video data instantaneously. Rather, after the recording for a week or so is completed, it is used to analyze an event if any event occurred during the period.
Although the device disclosed in JP-A-2-132599 can review the status before and after the event, it cannot deal with another subsequent event since it stops recording during the period.